A couple of weeks ago I was flipping through the pages of my local newspaper when I ran across an article by The Associated Press titled, “Oldest US diabetic ‘lifer’ reaches age 90.”

It caught my attention.

Back in 1926, a five-year-old boy by the name of Bob Krause was diagnosed with type I diabetes, (aka juvenile diabetes), shortly after the commercial production of insulin. Before that time children died of the nasty disease, including his brother.

As most of you may know, type I diabetes is different from type II diabetes. It’s a chronic illness in which the body no longer produces insulin, and life expectancy is shortened due to serious health complications that can develop as a result. However, Mr. Krause was determined to successfully beat it, and he’s now the oldest American known to live 85 years beyond the time of diagnosis.

I spoke with Mr. Krause over the phone to congratulate him and to discover his success tips, and guess what his number one tip has been? In fact, he calls it his “life’s motto”: he eats to live instead of living to eat! [And he'd never heard of a book with that title!] He always treats his body like a car and only eats enough food to fuel activities, and that’s it. For him, that equates to just two modest meals a day . . . not for pleasure; or emotional, social, or recreational reasons; and his fuel doesn’t consist of processed foods and lots of animal protein either.

Mr. Krause was determined from early on that he wanted to live the best life possible. And he did. He became a professor and established a career in teaching mechanical engineering at the University of Washington; plus, he and his wife raised a wonderful family together.

I was blown away by his positive attitude and wisdom of living with type I diabetes. He genuinely considers himself a blessed man to have had diabetes at such a young age as it caused him to do what he was supposed to do.

Before hanging up the phone, he told me that if all people would live as if they had diabetes, everyone would be a lot healthier. He said it’s each person’s decision to live or die, and that if we each do what we’re supposed to do, we’ll live a long and healthy life.

Congratulations Bob Krause – you are an inspirational hero!

By the way, he can’t understand why so many people have been making such a big fuss over him as he just did what he was supposed to do, to live!

When we use the word “metabolism,” we are usually referring to resting metabolic rate, which is the amount of energy (calories) that the body requires per day for its basic functions at rest. Most people believe that it is desirable to raise their metabolism, because they will burn more calories and consequently lose weight. Having a slightly lower resting metabolic rate is thought to predispose some individuals to weight gain, especially in the obesogenic food environment that we live in.1,2 However, there are unfavorable consequences to running your body at faster than normal speed, and raising your metabolism is not the key to weight loss.

Toxic byproducts of metabolism and biological aging

The chemical reactions of normal everyday physiology produce byproducts. In particular, cellular energy production produces reactive oxygen species as a byproduct, which can damage DNA, proteins, and lipids. Although we have natural antioxidant defenses, oxidative damage can still occur, especially if we don’t take in adequate antioxidants from our diet.3 Oxidative damage accelerates aging.

Aging here refers to biological aging – the progressive decline in the efficiency of the body’s physiological functions over time. This leads to tissue and organ damage, and increased risk of chronic disease and death.

Why do our bodies age? It is a combination of factors. One, the accumulation of oxidative damage over time damages the body’s tissues, leading to accelerated aging.4,5 And two, just the rate of living slowly wears out our cellular machinery, so if we function at a faster rate – i.e. a faster metabolism – the body will “wear out” more quickly. In animals, energy expenditure is indeed inversely related to lifespan, supporting this.6 Though both these mechanisms of aging are related, as a faster metabolic rate means faster energy turnover and greater production of free radicals, leading to increased oxidative damage.

Metabolic rate and lifespan

A study on thyroid function further supported the idea that a slower metabolic rate could prolong lifespan. Another study has measured resting metabolic rate directly and come to the same conclusion. Metabolic rate was measured by two different methods at the start of the study. Subjects were followed for 11-15 years, and deaths from natural causes were recorded. For each 100 calorie increase in 24-hour resting metabolic rate, the risk of natural mortality increased by 25-29%. These results strongly support the hypothesis that a slow metabolic rate promotes longevity.7

Do we have any control over our resting metabolic rate? How can we slow it down?

Resting metabolic rate is largely genetically determined, but our calorie intake has an effect as well.8 Caloric restriction and negative energy balance have been shown to reduce resting metabolic rate, and in contrast overeating increases resting metabolic rate.9,10 Furthermore, caloric restriction has been consistently shown to prolong maximal lifespan by up to 60% in animals.11 My findings have demonstrated that an optimal micronutrient intake reduces the desire for calories and reduces body temperature and white blood cell counts. This means that if follow a high-nutrient eating style that reduces calorie intake while meeting micronutrient demands, we can reduce our resting metabolic rate and potentially increase our longevity potential dramatically.

Keep in mind that although exercise raises total calorie expenditure, it does not raise the body’s basal metabolism. Exercise is the only safe way to “raise metabolism” because it activates the peripheral tissues to utilize more calories and also increases muscle mass which in turn increases total calorie expenditure.12 Plus, exercise promotes longevity.13

The goal here is to eat so healthy that it reduces your desire to overeat and reduces your metabolism slowly, so you can comfortably desire less food, though not get too thin. My nutritarian recommendations actually makes you more satisfied with less food, and actually gives the ability to enjoy food more without overeating.

So this study supports what I have said previously: having a fast metabolism does not mean that you are healthier – in fact, it probably means that you are aging more quickly. Instead of trying to increase your metabolism with the goal of losing weight, try to slow your metabolism with a low-calorie, high-nutrient diet for a longer, healthier life.

“Metabolism” has become quite a buzzword in our culture. Weight gain or inability to lose weight is often blamed on having a slow metabolism and the prevailing myth is that a faster metabolism is preferable, because it would lead to weight loss. However, having a fast metabolism does not mean that you are healthier – in fact, it may cause you to age more quickly. Many supplements claim to increase your metabolism and promote weight loss, but these are merely stimulants. Instead of trying to increase your metabolism with the goal of losing weight, I say, get your body to run on fewer calories and slow your metabolism for a longer, healthier life.

A study on thyroid function and longevity in families supports my view. This research is part of the Leiden Longevity Study in the Netherlands, in which recruited families had at least two siblings who were alive and had reached age 90 or older – these individuals are referred to as “nonagenarian siblings”.

Since thyroid function is influenced by genetics, and thyroid hormone regulates both basal metabolic rate (energy expenditure at rest with an inactive digestive system) and overall daily energy expenditure [1], the researchers studied thyroid function and longevity in nonagenarian siblings and their family members. [2, 3]

In a study published in 2010, it was established that middle-aged children of nonagenarian siblings had altered thyroid function compared to a control group. They tended to have higher levels of thyrotropin and lower levels of thyroxine (T4) and free triiodothyronine (free T3 – active form of the hormone), indicating lower thyroid function and therefore lower metabolic rate.[2]

A second study measured thyroid hormone levels in nonagenarian siblings and correlations to longevity of their parents. Low thyroid activity in nonagenarian siblings was indeed associated with their parents’ lifespans.[3] The average lifespan of the parents of nonagenarian siblings was an impressive 93 years.

These studies suggest that hereditary factors associated with metabolic rate (thyroid function) are associated with lifespan. This means that taking steps to slow metabolic rate, rather than accelerate it, could be beneficial.

How might a higher metabolic rate promote aging?

One theory is that increased energy expenditure shortens lifespan – that the human body works somewhat like a machine – if it is forced to work too hard and too fast, it will “wear out” more quickly. In a number of small mammal species, daily energy expenditure is indeed inversely related to lifespan, supporting this theory.[4] Accordingly, caloric restriction has been consistently shown to prolong maximal lifespan up to 60% in a variety of species.[5] By reducing calorie intake and still meeting micronutrient demands, daily energy demands are also reduced. Eating predominantly high nutrient, low calorie foods can help to achieve this effect – the body’s micronutrient requirements are satisfied with fewer calories, leading to reduced energy intake and therefore reduced energy demand.

Oxidative damage resulting from the continuous production of reactive oxygen species (as a byproduct of energy metabolism) over time is a related theory of aging.[6] A high nutrient diet would also be effective in this case, since whole plant foods provide both variety and abundance of antioxidants.

The point is we want to eat a diet with excellent micronutrient quality, we will not be hungry as often, we will be comfortable with eating less, and our metabolic rate will slow so that we can eat less and not get too thin.

Don’t buy into the myth – when it comes to metabolism, faster is not better.

Question: I have been exposed to the ideas fruitarians and raw foodies. I always figured that if I had enough self-discipline to practice these dietary philosophies. I would experience superior longevity, but a while back I learned popular fruitarian advocate T.C. Fry died at age 70. What gives?! If these dietary practices reap nothing in longevity beyond age 75, what hope is there for someone who doesn’t have a family history of longevity and is by no means as dedicated as prominent fruitarians and raw foodists?

Dr. Fuhrman: Being a fruitarian diet is not most healthful! I have seen lots of fruitarian, raw foodists in poor health, including one who died in his forties because he refused to take an antibiotic for his severe pneumonia. T.C. Fry died of severe Vitamin B12 deficiency, with resultant hyper-homocystiene causing vascular disease. I saw his hospital records before he died. He taught people they did not need to take B12. There are no guarantees, in life, but fruitarianism is not the answer.